A Quick Review of Type 3 Construction & Associated Fire Danger

Issue 9 and Volume 4.

In last month’s column (FireRescue, August 2009, “Warning Signs,” p. 116), I discussed two fundamental subjects that every fire department should cover in its training programs: fire behavior and building construction. Last month, I focused on flashover, which is just one small segment of fire behavior. This month, I want to follow up by talking a little about building construction.

Firefighters encounter thousands of buildings of every imaginable type. Some are hundreds of years old and some are brand-new, using the latest in engineering, construction techniques and building materials that we have little experience with under fire conditions.

The point: No matter how much knowledge and experience we have about building construction, there’s always more to know because it’s always changing. The more we know, the more we need to know.

Start with the Basics
Volumes are written on building construction as it relates to the fire service, but just reading books won’t teach you about your response area. Most U.S. cities are a mix of different construction types, each with their own special set of problems. As such, every firefighter should have a sound knowledge of each type and their inherent dangers.

Most buildings can be classified as one of five basic types:

  1. Wood frame (Type 1);
  2. Heavy timber/mill (Type 2);
  3. Ordinary (Type 3);
  4. Noncombustible (Type 4); or
  5. Fire-resistive (Type 5).

One of the most difficult concepts to teach firefighters about construction types is that although every building should be able to fit into one of these types, it’s also common to find features of multiple construction types in one building. This is especially true with new construction or buildings that have been renovated.

When building construction is your training topic, always start by ensuring that your crew knows and understands the fundamentals of each type of construction, as well as how each type may incorporate features from other types.

Not So Ordinary
This month’s drill will focus on ordinary construction, also called Type 3. A general definition of ordinary construction: a building featuring exterior masonry walls and combustible interior beams or truss. Although it’s not the most often used building type today, Type 3 construction has been used a great deal for commercial buildings built in the last 2 centuries.

Ordinary construction is Main Street USA. You can find some form of it in just about any city in the country, from old schools made of hand-cut stone walls with simple beams that span the width of the building, to new strip malls with pre-cast blocks and lightweight engineered wood trusses. Techniques used to construct these buildings vary greatly from one part of the country to another because of the building materials used. Older Type 3 buildings still in use today were built using local materials easily accessible to the builders.

Ordinary construction buildings have a long history of difficult fires. As well as the combustible nature of the construction, you’ll often find a very heavy fire load in these buildings. Here are a few discussion points to cover about ordinary construction at drill time.

Void Spaces. Just like in a balloon frame house or really any wood-frame building, Type 3 buildings feature lots of void spaces created by the construction process. Combustible void spaces between floors and in the attic are places where fire can go undetected and be difficult to reach.

Masonry Walls. The load-bearing exterior masonry has a huge potential for collapse. Don’t put a lot of faith in rules of thumb concerning time limits when operating in these structures. If operating defensively, pay close attention to apparatus placement and deployment of crews in flanking positions outside the collapse zone.

The masonry walls serve both to carry the load of the building and prevent fire extension into adjoining buildings. But don’t trust these walls to hold the fire. Over time, the walls will start to deteriorate, allowing the fire to find places to pass though.

Renovation: Buildings are changed to meet the needs of the occupants. Each time we see a building under renovation, changes are being made from its original design that may affect the way the building will react under fire conditions.

Example: lowering or dropping of ceiling heights. If the building code doesn’t require ceilings to be removed, most owners will choose to leave them in place to avoid the cost of removal. Multiple ceiling areas are perfect places for fire to extend into and grow overhead while crews operate below, unaware of the growing danger. These drop-ceiling areas are also very difficult to open up if fire has extended into them. Make sure your crews have the right tools and equipment to face this issue—and the training to support them.

Drill 1: A Typical Review

  1. Discuss each type of building classification (1 to 5) and the method of construction for each.
  2. Review the inherent dangers associated with each construction type during fireground operations.
  3. In your response area, identify buildings that can be classified in each of the types.

Drill 2: Focus on the Ordinary

  1. Review the basic definition of a Type 3 (ordinary) building as it relates to the fire service.
  2. Working off a good photograph or in front of an actual Type 3 building in your area, have each member identify five features on the building that could lead to problems. Examples: lintels made of steel or wood, eccentric loading such as canopies, existing wall cracks or cast-iron building fronts.
  3. With the entire company, review indicators of possible collapse. Also discuss apparatus placement and where collapse safety zones should be set up to protect personnel.

There are many aspects of ordinary construction that firefighters must understand to be ready to face the next incident in a Type 3 building. Make sure you take the time to study and reinforce their book knowledge with good company-level training on building construction. Use your time out on the streets to identify and preplan the Type 3 buildings in your response area.